Charging system for an implantable medical device employing magnetic and electric fields

Abstract

A base station for passively recharging a battery in an implant without patient involvement is disclosed. The base station can be hand held or may comprise equipment configured to be placed at a fixed location, such as under a bed, on or next to a wall, etc. The base station can generate electric and magnetic fields (E-field and B-field) that couple with an antenna and a receiving coil within the implant to generate a charging current for charging the implant's battery. No handling or manipulation on part of the patient is necessary; the implant battery is passively charged whenever the patient is within range of either the magnetic or electric charging fields generated by base station. Charging using the B-field occurs when the IPG is at a relatively short distance from the base station, while charging using the E-field occurs at longer distances.

What is claimed is: 
     
       1. An implantable medical device, comprising:
 a battery; 
 a first antenna configured to receive an electric field for charging the battery; 
 a second antenna configured to receive a magnetic field for charging the battery; and 
 a microcontroller for determining whether either or both of the electric field and the magnetic field have been received at the first or second antennas respectively, and for issuing at least one control signal enabling charging of the battery either by the electric field or the magnetic field. 
 
     
     
       2. The device of  claim 1 , further comprising a first rectifier coupled to the first antenna for producing a first DC voltage, and a second rectifier coupled to the second antenna for producing a second DC voltage. 
     
     
       3. The device of  claim 2 , wherein the microcontroller determines whether either or both of the electric field and the magnetic field have been received at the first or second antennas respectively using first and second DC voltages. 
     
     
       4. The device of  claim 2 , further comprising charging circuitry, wherein the charging circuitry is responsive to the at least one control signal to select either the first DC voltage or the second DC voltage as the power source for charging the battery. 
     
     
       5. The device of  claim 1 , wherein the at least one control signal enables a transmitter for transmitting charging information from the implantable medical device. 
     
     
       6. The device of  claim 5 , wherein the transmitter transmits the charging information from either the first or second antenna. 
     
     
       7. The device of  claim 1 , wherein the charging information comprises a voltage of the battery. 
     
     
       8. The device of  claim 1 , wherein the first antenna comprises an electrode lead coupled to an electrode for providing stimulation to a patient's tissue. 
     
     
       9. An implantable medical device, comprising:
 a battery; 
 a first antenna configured to receive a first field for charging the battery, wherein the first field is less than or equal to 100 kHz; 
 a second antenna configured to receive a second field for charging the battery, wherein the second field has a frequency ranging from 1 MHz to 10 GHz; and 
 a microcontroller for determining whether either or both of the first field and the second field have been received at the first or second antennas respectively, and for issuing at least one control signal enabling charging of the battery either by the first field or the second field. 
 
     
     
       10. The device of  claim 9 , further comprising a first rectifier coupled to the first antenna for producing a first DC voltage, and a second rectifier coupled to the second antenna for producing a second DC voltage. 
     
     
       11. The device of  claim 10 , wherein the microcontroller determines whether either or both of the first field and the second field have been received at the first or second antennas respectively using first and second DC voltages. 
     
     
       12. The device of  claim 10 , further comprising charging circuitry, wherein the charging circuitry is responsive to the at least one control signal to select either the first DC voltage or the second DC voltage as the power source for charging the battery. 
     
     
       13. The device of  claim 9 , wherein the at least one control signal enables a transmitter for transmitting charging information from the implantable medical device. 
     
     
       14. The device of  claim 13 , wherein the transmitter transmits the charging information from either the first or second antenna. 
     
     
       15. The device of  claim 9 , wherein the charging information comprises a voltage of the battery. 
     
     
       16. The device of  claim 9 , wherein the first antenna comprises an electrode lead coupled to an electrode for providing stimulation to a patient's tissue. 
     
     
       17. The device of  claim 9 , wherein the first field comprises an electric field, and wherein the second field comprises a magnetic field.